It's the most wonderful time of the year — to call it quits? Four celebs will be ringing in the holidays minus their plus one, and USA TODAY's Andrea Mandell checked in with HollywoodLife.com's Bonnie Fuller to find out how love went so wrong for these couples.

Ex files: Last Monday, one of Disney's most sizzling love connections officially fizzled, according to E!. After meeting on the set of 2006's High School Musical, Efron and Hudgens were mum on their romance for years — until recently. "Right off the bat, we had a connection. I think everybody could see it," Hudgens told Glamour this year. As hotly watched as Twilight's Robert Pattinson and Kristen Stewart, the two were photographed taking in Lakers games, vacationing in Hawaii and mugging at the premiere of Efron's latest flick, Charlie St. Cloud. But this summer the clean-cut Efron was caught visiting a strip club in New York and later 'fessed up on Jimmy Kimmel with a sheepish grin, saying Hudgens "was fine with it." He also told GQ last year that he intended to take it slow. "I'm not getting married until I'm 40," said Efron. "If ever. The thought never crossed my mind."

Expert opinion: "They made it for quite a long time considering they were so young," says Fuller. "I think it ran its course, and at a certain point they realized they're too young to settle down." But there's an upside: "They both have good career paths."

Awkward factor: Low. "I think we're going to see them still hanging out," says Fuller. "From everything we hear, they're still friends." Hudgens seconded that in Vegas this weekend while celebrating her birthday. "We're good," she told People.

Ex files: Theirs was a wedding that was hard to forget.After dating since 2003, Hurley and Indian businessman Nayar had a fairy-tale wedding at a castle in England in 2007, followed by a lavish week-long celebration in Nayar's native India. But when a British tabloid recently published shots of Hurley kissing cricket player Shane Warne, the actress and model took to her Twitter account to set the record straight: she was not cheating. "Not a great day," she wrote on Dec. 12. "For the record, my husband Arun and I separated a few months ago. Our close family & friends were aware of this." The two reportedly do not have a pre-nuptial agreement. "I think it's shocking that he didn't have a pre-nup," says Fuller. "She's going to make out like a bandit." For Hurley's part, she says divorce is not imminent. "Bored now of silly speculations: no one is divorcing anyone yet, no one is fighting over money ... Enough!" she tweeted on Dec. 16.

Expert opinion: Fuller calls the turn of events "very strange." "Apparently they split months ago," she said, noting that Hurley's son Damian, 8, is losing his "acting father figure." (His birth father is Steve Bing.)

Awkward factor: Low. "Listen, she has a history of staying good friends with her exes," says Fuller, noting "she's still very close to Hugh Grant," who famously cheated on her. They dated for 13 years. "He's her son's godfather."

Ex files: Not even People's 2010 Sexiest Man Alive could keep marriage to his "best buddy" from hitting the skids this year. The super-secretive couple surprised many when they married in a quiet ceremony in Vancouver in September 2008, and they have resolutely kept their mouths shut in interviews since. "Nobody knows (how we met)," Johansson told Allure in 2008. "It's private. It's our story." Rarely captured by photographers, the two attended only a handful of events together, including last year's Tony Awards, where Johansson scooped a best-actress trophy for her role in A View from the Bridge and called Reynolds "my Canadian." But both have packed schedules: she stars in 2012's The Avengers; he's called his "very physical" work on 2011's Green Lantern "a long haul." Post-breakup, Johansson took off to Jamaica with friends, but the two were spotted dining in NYC together on Friday.

Expert opinion: Fuller says it's telling that they were rarely in the same frame. "Either they were very intent on not being photographed together (a la married couple Gwyneth Paltrow and Chris Martin), or the other reason is they were simply never together," says Fuller. "Career-wise, they're both doing really well."

Awkward factor: Medium. "Luckily, they're going to be able to avoid each other pretty well," unless they're on the same red carpet, says Fuller, noting that even exes Jennifer Aniston and Brad Pitt have managed to keep their distance at big Hollywood events.

Ex files: The co-stars, who play brother and sister on Dexter, admitted they were reluctant to start a romance and secretly dated for a year and a half before tying the knot. "But in the end, the heart wanted what the heart wanted," Carpenter told the Los Angeles Times in November. Carpenter nursed Hall during his treatment for Hodgkin's lymphoma, and he even singled her out in his Golden Globe acceptance speech in January. But on Dec. 13, the two released a joint statement: "Having been separated for some time, Jennifer Carpenter and Michael C. Hall have filed for divorce."

Expert opinion: "It's very stressful to have a partner who goes through a serious illness," says Fuller, noting that problems in the relationship could have been put on the back burner while Hall got healthy.

Awkward factor: High. "They're just like any couple that meets in the workplace," says Fuller. (Think Gossip Girl's Blake Lively and Penn Badgley, who broke up in October, or Jennifer Garner and Michael Vartan, who dated and split while shooting the TV series Alias.) "It's extremely difficult to carry on working together when you're on the same TV show, but it's not unheard of."

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